Sweet Poison
by FallingHero64564
Summary: Finn goes missing after attempting to reach out to the Gumbaldian's. Concerned for her people, Princess Bubblegum agrees to the treaty if only to benefit from Gumbald's military. (Fern, Aunt Lolly, Chicle, and The Emissary are all present, but due to the tagging system are not tagged)
1. Chapter 1

Summary- Finn goes missing after attempting to reach out to the Gumbaldian's. Concerned for her people, Princess Bubblegum agrees to the treaty if only to benefit from Gumbald's military and Fern.

 **AN: warning for abusive behavior, manipulation, and grooming. Human experimentation is also going to come up but not to the same extent as those three. This chapter also contains underage drinking. Tread with caution.**

* * *

The bubblegum family seemed delighted to listen to Finn's story, the three of them seemed so laid back now. It was hard to believe only hours ago they were ready to have Fern kill him just for approaching their palace. Finn avoided drinking anything they offered him, but Jake had no hesitation.

Gumbald cleared his throat. "Finn, your talent for diplomacy is not what I expected. My memory is of someone much more fond of violence than you seem to be."

He smiled politely and looked away. Something in Gumbald's eyes reminded him of the beasts he used to fight so often. Finn tried to squash the feeling, blaming it on PB'S paranoia. "Thanks, I just want to keep everyone safe, y'know?"

"Yes, I can understand the feeling. Finn, You have convinced me to call off war preparations against the candy kingdom. Why don't we discuss the details in my study?"

"Oh sure! Jake, are you coming?" Finn stood, hoping his brother would pull himself away from the table to back him up.

Jake shoved another tart into his mouth. "I'll catch up with you later. Aunt Lolly, your cooking is divine."

Finn was dragged off by Gumbald as Jake and Lolly began exchanging recipes excitedly over the banquet in front of them. The strange base that Gumbald used to build his kingdom went fairly deep underground, many rooms seemingly empty. It was reminiscent of the dungeons Finn was so adept at but instead of silence it was filled with noises of construction and preparation. War was being born in these walls.

He shuddered at the thought. It was not the future he wanted for Ooo, another war on the same caliber as the Great Mushroom war would leave the land in tatters. Ooo was only just recovering from the last one.

Gumbald led him into a room that seemed rarely used. The walls were lined with shelves holding books in languages Finn had never heard of. In the center of the room was an ornate desk. A fireplace erupted to life as the pair entered the room. "Please, make yourself comfortable. I wasn't expecting to have to draft a treaty so please forgive the state of my study."

"Ah, no it's nice." Finn slipped into a chair near the fireplace, taking in his surroundings. "it reminds me of Simon's library… uh do you know Simon?"

"I'm afraid not. After we have this treaty mess sorted out, perhaps you can fill me in on the goings on around Ooo."

Finn relaxed a bit, smiling. "Sure."

As the pair discussed a variety of things to be included in the treaty, trying to include things that Finn was certain PB would agree to. Once they found an agreement that seemed to be satisfactory, Gumbald suggested that they celebrate, pulling out a bottle of strange liquid from a drawer. "Aunt Lolly is quite adept at creating new recipes, she calls this 'Sweet Malt' I'm sure you'll enjoy it."

"Oh um, I don't think…" Gumbald handed him a silver cup of the drink before he could refuse. Finn took a sip out of obligation, flinching at the burning sensation. The taste was good but left behind some bitterness. _If they didn't poison us at dinner I'm sure this is fine, right?_ He took another sip.

"… write a letter?"

Finn jolted out of his thoughts. "Sorry, what did you say?"

"I asked if I should write a letter to Bonnibel. To apologize for everything? Would that make me seem more trustworthy?"

"I guess," _Was his drink supposed to sparkle like that?_ "I'm sure she'll warm up to you when she sees the treaty though." His next sip made him feel lightheaded, which worried him. He decided to set his drink to the side. "She's nice…"

"Of course," Gumbald rolled up the signed treaty and letter- _when did he finish writing that?_ \- before slipping them into a round canister. "Finn its been such a pleasure meeting you. I'll have Fern escort you home. Give Bonnie a big hug when you tell her."

Finn stumbled a bit, knocking over the goblet. The carpet seemed to sparkle where the drink fell. His suspicions rose when Gumbald jerked away from the stain. Gumbald had no intention of peace, he was trying to kill him. He'd been poisoned.

Before he could try to escape, he found himself collapsing into Fern's arms. "Where should I take him?"

"Just keep him out of Jake's sight for now. Try to keep him intact."

As Finn lost consciousness, he felt himself be slung over Fern's shoulder. He donked up...

* * *

"Finn?" Jake glanced around the Gumbaldian Palace, ducking his head into almost every room. "Where are you buddy?"

As if to mock him, Fern rounded the corner at that very moment. The grassy knight seemed frustrated. He didn't even seem to notice when he almost ran into Jake. "Oh, it's you."

"Fern! Hey buddy, could you help me find Finn? Last I saw, he was going somewhere with Gumbald to talk about a treaty."

A Canister popped out of the Knight's chest; thin vines holding it in place as Fern plucked it out and handed it to Jake. "Finn already left. He forgot to take this with him though. Maybe you can still catch up to him?"

"Thanks man!" Jake took the canister and raced towards the exit. Once outside, he continued his search for Finn from above. He stretched up high enough that he could see from a distance. Jake tried not to worry, Finn was seventeen after all. But something inside kept nagging at him. _Hmm... maybe I should go back. No, he could've taken a different route. I'll just catch up with him at PB's castle._

Upon arriving at said castle, Jake was greeted to the sight of even more war preparations. He stretched his way to PB, unsurprised to find her overseeing the preparations. "Double check the fortifications of the outer walls,"

"One signed peace treaty, delivered straight from Gumbaldia!" Jake dangled the canister in front of the frazzled princess.

"What?!" She snatched the canister away from him, tore it open, and began reading fervently. "How... Where did you get this?"

"Finn didn't tell you? He wanted to try a last ditch diplomacy thing to get you two to settle down."

She stared at the treaty in awe. "He did it... he got Gumbald to stand down." Her eyes snapped up to Jake. "Where's Finn? Glob, I could hug him right now!"

"Heh, figures I got here before him. Serves him right for leaving without me. He'll probably show up later."


	2. Chapter 2

**AN: Warning for this chapter; threats of violence, manipulation, general creepiness from Chicle.**

Fern was glad that he didn't have eardrums. If he did, they would be bleeding at the sound of his human counterpart's scream of terror. He transformed one arm into a vine to restrain him and his blade arm pressed against the human boy's cheek. "Shut up, or I'll give you a reason to scream."

The boy's screaming softened into whimpering. "Who- What are you?"

Fern opted to ignore him, deciding that Gumbald would be the one to handle this mess. He flinched when the door slammed open and Aunt Lolly scurried in.

"Oh dear. I heard what... happened. Fern, you haven't done anything to him yet have you?"

"Just told him to shut up. He's fine." Fern materielized various weapons in a not so subtle attempt to intimidate his 'brother'.

Aunt Lolly's presence seemed to calm Finn down dramatically. _Is it because she reminds him of Mom? Or because she looks human?_ Either way, his counterpart was relaxed enough that he seemed to be observing Fern through new eyes. "Who are you? Are... you going to hurt me?"

"Of course not dear!" Aunt Lolly reached out of the room and brought in a cart of food. "We're your family! Fern is your Big Brother so he's just grumpy he's not the only one now. You can call me Aunt Lolly."

Finn calmed down considerably as he ate. Fern's irritation only built as the Human continued to ask questions about everything. Lolly seemed unfazed by the questions and answered them without issue, forging a story about who Finn was and why he was there. She threw in a few details about how dangerous it was for him to leave the palace, listing out things that might want to hurt him. If those things happened to include some of Finn's closest friends it was purely coincidental.

When Gumbald and Chicle entered, Finn reacted with suspicion. _Dum-dum juice must not be as effective on humans. He's still capable of recognizing threats. I'll have to play along if I want to get him alone again._ His role had already been established. Fern was, like Finn, an 'attempt to recreate human life'. _Big brother Fern... funny how he's getting the connection he wanted in a sort of roundabout way._ The two Gum men had wildly different reactions to Finn's new ignorance. Gumbald seemed to already be scheming about how to use Finn. While Chicle on the other hand seemed... excited. Like a child given a new toy.

"We'll give you some time to settle in." Aunt Lolly grabbed her 'husband' and 'son' and began to drag them out. "Come along Fern. Finn needs so time to himself."

Once outside Gumbald began to gush. "It worked like a charm! He's completely at our mercy. With him, I'll be able to create candy people far more advanced than those peasants Bonnibel has scurrying about."

Aunt Lolly frowned. "Why didn't we just go with my plan? With the treaty in effect, we'll have to stand down. Not to mention, she'll notice if her champion doesn't return and will suspect us."

"Not if we offer to help find him. After all, he left _such_ an impression on us. We'd be _devastated_ if something were to happen to him." Chicle offered.

Gumbald nodded in agreement. "We watched him leave to tell Bonnie the good news, it's not our fault that he has so many enemies who wish him ill."

"Liiiike, Sir Slasher? Or maybe Ricardio?"

Fern scowled. He was on that list of enemies. Would they throw him under the bus once they thought he wasn't needed? He glanced back at Finn's room. "What do you plan to do with him now that you have him to yourself?"

Chicle grinned in a way that reminded Fern of the way LSP looked at Finn. "What can't we do? He's so pliable now, we can convince him to be anything we want."

"First," Gumbald cut in. "We are going to ensure that Bonnibel does not and will not suspect us. Then, I will begin studying him. Until then, Lolly will be in charge of ensuring his loyalty to us and that he doesn't make his presence known to the outside world."

* * *

Finn felt out of place in the room he'd woken up in. It had no windows, it was too neat, there were very few items on the wall outside of pictures of the bald man he'd met. He felt like... he was trapped.

 _Not trapped. They're keeping me safe! Outside are Vampires, and witches, and mad scientists who'd love to get ahold of me._ He frowned. _I should try to be helpful... Helping. Yeah, that feels right._

He explored the bathroom, finding the bare essentials stocked in a cabinet. After he showered and dressed in the loose pants ( _too long, boring color_ ) and warm cloak( _No shirt?_ ) he'd been given, he noticed a small pile of books. With those books came a revelation...

Finn _hated_ reading. Only a few pages in and he felt like his soul was begging to be put out of his misery. He shouldered on reading despite not understanding half the words in the dense text. Aunt Lolly came in a few hours later to find him stubbornly attempting to continue reading, even though he'd barely gotten half way through.

"Are... you alright dear?" he nodded. "Why don't you take a break and eat something?"

"Okay."

* * *

Banana Guards swept the area around the castle calling out for the Champion of their princess. Jake was also participating in the search, sending a message to his Pups to keep an eye out for their uncle. Meanwhile, Bubblegum awaited news of her friend's safe return. She tried to focus on reinstating a more peaceful mindset in her populace(Finn probably worked very hard to get that treaty, she couldn't just throw it away.) but doubt took hold of her mind.

She wanted to believe the best, he was probably lost or got distracted helping someone. But she couldn't trust her family. If Finn went missing under their care it couldn't be a coincidence. Her eyes continued to drift to the treaty, noticing one of the inclusion of one thing in particular... Shared military forces. _But if Finn had returned that would also include him wouldn't it? Why would they capture him and not Jake? What could they possibly gain from imprisoning him if they wanted peace?_ She groaned. It didn't make sense. The treaty made them look innocent, if she made a move against them it would put her in the wrong.

Her hands were tied.

"Peps?"

"Yes, Princess?"

"Make a copy of the treaty. I want to send them a signed document."

Her loyal servant was shocked. "Are you certain princess? What if they're..."

"I know but if Finn doesn't reappear soon, and some new threat shows up, we're going to need the Green Knight." She signed the document next to Gumbald's, officially accepting the truce. _Please be okay, Finn. This is the least I can do right now. When you come home you'll have the peace you wanted._


	3. Chapter 3

**AN: some references to past trauma in this chapter but its pretty light.**

Hours turned into days turned into a week with no sign of their hero. Princesses began to worry that soon Ice King would revert back to his old ways without the Human around to keep him in check. Banana Guards became jittery when even the smallest threat showed up. Jake and Jermaine were running ragged trying to find their brother.

All the while, Bonnie's suspicion of her traitorous family skyrocketed. Their weapons production had grinded to a halt and soon she discovered that they had begun to build warehouses to stockpile what weapons were already completed. Aunt Lolly stopped appearing publicly and Chicle seemed almost eager to interact with his creator/cousin.

It was all too perfect.

Bubblegum glared her uncle down as he approached with the Green Knight in tow. Just because they had a treaty doesn't mean she had to like him. Marceline hung around, draping herself over Bonnie protectively.

She didn't give him a chance to speak before she announced: "Finn is missing."

Gumbald had the audacity to act surprised. "Oh no, is there anything we can do to help?"

"We have some suspects. We'd like Fe- The Green Knight's help to bring them in." She strode forward and held up the treaty. "You did offer to share military forces."

"I did." Gumbald didn't seem fazed in the slightest. _Of course he expected this. But I can't do anything unless I have proof he's holding onto Finn. Or unless we find a body._ "My Green Knight will preform Finn's duties until the boy is found. It's a shame though. I was hoping he could tell me more about this modern day Ooo. I haven't had much time to learn about what happened while I was... indisposed."

Bonnie felt her chest clench in fear remembering that day, 800 years ago. She had been so alone in that moment. The family she had tried to build had crumpled before her eyes. Her own ambition, given form, destroying what she had wanted to create. Marceline wrapped her arms around her shoulders again, bringing her back from the terror of the past. She leaned into her friends touch a bit more than would be acceptable under normal circumstances... but damnit, she needed this.

"Thank you, Uncle."

Once the Gumbaldian's left, Bonnie buried her face into Marcy's hair and lost control. "He was so close.."

Marcy scooped her up and held her. For a moment Bonnie let herself imagine if things hadn't gone wrong. If they had been able to work things out all those years ago. If she had her family... would she have had the time to be with Marceline? Could this moment have been sweeter? In that moment she hated Gumbald more than anything for turning her into a crying little girl just by existing.

"Hey, It's gonna be okay. We'll find Finn and then we'll find a way to kick Gumwad's ass." Marceline tilted Bonnie's head up and they made eye contact. "Finn is stubborn, he's not gonna let somebody like him take him down."

* * *

Day to day in the palace was rather simple to get used to. Finn was sad that he didn't get to see Fern around that much(even if he found his bright red color slightly intimidating). Family was supposed to spend time together, at least according to Aunt Lolly. Lolly always got really sad when talking about family but she always cheered up once he asked he could help with whatever tasks she was doing. She felt safe.

Nights were a different story.

Dreams of rolling fields and strange creatures plagued him at night. Whispered warnings from a green woman echoed in his thoughts. A door to a vault that hid many secrets, sealed shut with unbreakable chains. In his dreams his right arm was made of _grassmetalflesh._

Some nights he felt like he was being pulled around and forced to dance to song he couldn't hear. Others he was a child who couldn't speak and pleaded to be heard while those around him looked down on him, amused by his failures.

He avoided sleeping when he could, instead learning the many passageways between rooms of the palace. His favorite was the one that let him see the stars. Some nights he heard a voice singing in the distance when he was up there.

"How did you get up here?"

Finn's head snapped around to see Fern emerge from the same hidden escape as him. "Are you here to see the stars too?"

"That's not.." Fern stopped and his form shivered a moment. "I heard someone out here, turns out it's just _you_."

"I don't think she's singing yet. If you stay you might hear her."

Fern stared at him for a while. "Are you listening to a word I'm saying?"

"Shhh, you'll miss it if you keep talking."

The Knight stomped over to him and grabbed his arm. "You're coming back inside with me, you shouldn't be out here." Instead of struggling, Finn simply refused to move, forcing Fern to drag him. His brother kept trying to force him to stand up and walk but he didn't react outside of a stubborn pout. "If you don't stand up I'll throw you down this hole."

"There's nothing to do inside. I want to stay out here."

"No."

Finn wiggled out of Fern's grip and laid back on the ground to stare at the sky. "An Hour."

"NO." He ignored him. "Why are you even out here?"

Finn didn't respond, deciding to listen for the singing.

 _Come Along With Me_

 _To a town beside the sea_

Fern sat next to him, still irritated that he wasn't getting a response.

 _We can wander through the Forest_

 _and do so as we please._

 _"Come along with me_

 _to a cliff under the sea_

 _where we'll gaze upon the water_

 _As an everlasting dream."_ He sang with the voice, his brother apparently unable to hear it.

 _All of my affections_

 _I give them all to you_

 _maybe by next summer_

 _we won't have changed our tune_

 _Cause we'll want to be_

 _in the town beside the sea_

 _making up new numbers_

 _and loving so merrily_

"I want to see that town someday."


	4. Chapter 4

**AN: Pretty please RR I'm feeling a bit self conscious :(. also... *pointing at simon* that's a dad if i ever saw one.**

warning: death implied

It was months since the search for Finn had begun, dead end clues leading nowhere as Fern and the Gumbaldian's feigned helpfulness. But danger was ever present in Ooo and when King Man appeared warning of the arrival of Golb, the kingdom's scrambled to amass the forces needed to hold him back... but it backfired catastrophically.

Fern watched the people descend into chaos as the being descended from the heavens, Banana Guards and Cake Soldiers were absorbed into the mass of a horrifying pulsating creature. It was nightmarish and all a manner of creatures fled in panic as it began to rampage and absorb more creatures into itself. His body and mind thrummed with excitement. **_A challenge._** He conjured his weapons in anticipation. **_Kill the evil._**

"Wait." Gumbald held up a fist to halt Fern. "This could work in our favor. Bring me Ice King."

 ** _No. KillKillKillKILLKILLKILL!_** "I can take this thing." Fern hissed. _Do you doubt me? **foolish.** I've killed things far more powerful than you. **Eliminate him-.**_

"I'm sure you can, but we could use this creature."

He swallowed his frustration. **Fine"** Racing off to find the wizard, he tried to quell the desire to simply ignore Gumbald's instructions. The creature swiped at him and lost its arm in the process. As it recoiled in pain he raced to retrieve cursed scientist.

"Fern! Look out!" Jake stretched out like a tarp to block a swarm of demonic birds from pecking him to bits. His brother shrieked in pain. "War is hell, man!"

"Jake!"

In the distance he noticed Ice King flying up towards the creature. He decided to help his brother rather than continue to comply with Gumbald's commands. _He won't know. **If he puts up a fuss we could kill him.**_

His vines shredded the creatures attacking Jake to bits, while the creature corrupted one of PB's gumball guardians. "Oh, Thanks Fer- Uhh, Green Knight."

"Keep up." He raced towards the Corrupted Guardian, weapons at the ready.

Fern reveled in destroying the creature, even as it respawned over and over from it's own remains. eventually it managed to land a good hit, knocking him away like an ant. He could only watch as it continued to rampage, eventually destroying the Treehouse in its senseless destruction. **"No!"** He attempted to race after them, rage boiling over. It was personal now. _Is BMO Ok? Where's Neptr? **If they hurt them I won't leave anything for them to come back in.**_

"Everyone!" Fern froze at the sound of PB's voice echoing over the battlefield. "I need you all to Harmonize with BMO!"

Relief washed over him as the tiny robot began to sing, the survivors chiming in with their own voices. Fern joined in as loudly as he could.

 _If there was some amazing force outside of time,_

 _To take_ _us back to where we were._

 _And hang_ _each moment up like pictures on the wall_

 _Inside a billion tiny frames so we can see it all, all, all_

 _It will look like, will happen, happening happen._

 _Will Happen, happening, happened._

 _And there we are, again and again_

C _ause you and I will always be back then._

And then the world went white.

 _"Betty look! We can escape this way."_

 _"I'm sorry, Simon. I need to do this."_

"Betty!" Simon lunged forward to try to stop the love of his life. But it was in vain.

He collapsed back on the bed that Marcy had set up for him. How long ha he spent wallowing in his adopted daughters home, not making a single move to further his new life in this world. Maybe he could return to his research?

No... it wasn't the same without her. What was the point?

"Simon?" Marcy floated into the room, concern etched into her features. "Are you ok?"

"I'm fine, Marcy. Don't worry about me." He suddenly recalled a memory from his time as Ice King. "Are you okay? Your... friend is missing right? Uh, Phil right?"

Marcy sighed and sat down next to him. Instinctively, Simon pulled her close and shielded her body with his. She hugged him back. "I wasn't ready for it to happen. I thought we'd have more time with him... he was still so young." She squeezed him. "I'm tired of loosing people, Simon. Bonnie... I could lose her at any moment and I'm just... I'm not ready."

"Hey hey," He stroked her hair, partly glad that he could distract himself by focusing on someone else and partially angry that his little girl was so distraught. Really it leaned more towards the later. "You can't spend all your time worrying about the future. How will you enjoy the time you have with them already? Besides, your friend could still be out there."

"It's not that simple... Finn should have busted himself out by now. Something's wrong but we can't do anything about it or else it'll start a war worse than the Mushroom War."

Simon pinched the bridge of his nose, politics were never his forte. "Ok... walk me through this."

The pair stayed up for hours as Marceline explained the history of the Bubblegum family and the events leading up to their return. She explained the existence of Fern the Human(not to be confused with Finn the Human, they stopped being the same a long time ago.) and how he allied with them to get revenge on Finn.

"So you think that Fern killed Finn, and the Gumbaldians are covering it up. But since you can't defend Ooo in Finn's place, due to your vampiric nature you're all playing along to use the Green Knight as a stand in until you can find proof and justify killing the Bubblegum family once and for all."

"When you put it like that..." Marceline looked ashamed.

"How can I help?"


End file.
